1. Field of the Invention
The present invention relates to the field of laser interferometers and more particularly to the optical path configuration in ring interferometer employing optical waveguides.
2. Description of the Prior Art
As early as 1925, Michelson and Gale fabricated a large interferometer which measured the fringe shift created in a beam of light due to the speed of rotation of the earth. Since that time, it has been appreciated that an inertial gyroscope may be fabricated using a ring interferometer. A typical example of a prior art ring interferometer can be seen in U.S. Letters Pat. No. 3,102,953.
The sensitivity of a ring interferometer can be increased by increasing the area enclosed by the ring. Prior art interferometers have employed multiple looped paths of fiber optics or mirrors. In such configurations stability and attenuation over long path lengths limit the ability of achieving large enclosed areas. Moreover, the temporal coherence of a beam is difficult to maintain to such prior art interferometers which are multimode light guides over a long path.
Therefore, what is needed is a configuration for a transmission path for an inertial rate sensor, such as a ring interferometer, which may be fabricated in a small space, which will be stable, single mode and relatively inexpensive without sacrificing the sensitivity achievable by the larger inertial rate sensors.